IBM PC

IBM PC

(computer)

International Business Machines Personal Computer.

IBM PCs and compatible models from other vendors are the most
widely used computer systems in the world. They are typically
single user personal computers, although they have been
adapted into multi-user models for special applications.

Note: "IBM PC" is used in this dictionary to denote IBM and
compatible personal computers, and to distinguish these from
other personal computers, though the phrase "PC" is often
used elsewhere, by those who know no better, to mean "IBM PC
or compatible".

There are hundreds of models of IBM compatible computers.
They are based on Intel's microprocessors: Intel 8086,
Intel 8088, Intel 80286, Intel 80386, Intel 486 or
Pentium. The models of IBM's first-generation Personal
Computer (PC) series have names: IBM PC, IBM PC XT, IBM PC AT, Convertible and Portable. The models of its second
generation, the Personal System/2 (PS/2), are known by model
number: Model 25, Model 30. Within each series, the models
are also commonly referenced by their CPUclock rate.

All IBM personal computers are software compatible with each
other in general, but not every program will work in every
machine. Some programs are time sensitive to a particular
speed class. Older programs will not take advantage of newer
higher-resolution display standards.

The speed of the CPU (microprocessor) is the most
significant factor in machine performance. It is determined
by its clock rate and the number of bits it can process
internally. It is also determined by the number of bits it
transfers across its data bus. The second major performance
factor is the speed of the hard disk.

CAD and other graphics-intensive application programs can
be sped up with the addition of a mathematics coprocessor, a
chip which plugs into a special socket available in almost all
machines.

Intel 8086 and Intel 8088-based PCs require EMS
(expanded memory) boards to work with more than one megabyte
of memory. All these machines run under MS-DOS. The
original IBM PC AT used an Intel 80286 processor which can
access up to 16 megabytes of memory (though standard MS-DOS
applications cannot use more than one megabyte without EMS).
Intel 80286-based computers running under OS/2 can work
with the maximum memory.

Although IBM sells printers for PCs, most printers will work
with them. As with display hardware, the software vendor must
support a wide variety of printers. Each program must be
installed with the appropriate printer driver.

The original 1981 IBM PC's keyboard was severely criticised by
typists for its non-standard placement of the return and left
shift keys. In 1984, IBM corrected this on its AT keyboard,
but shortened the backspace key, making it harder to reach.
In 1987, it introduced its Enhanced keyboard, which relocated
all the function keys and placed the control key in an awkward
location for touch typists. The escape key was relocated to
the opposite side of the keyboard. By relocating the function
keys, IBM made it impossible for software vendors to use them
intelligently. What's easy to reach on one keyboard is
difficult on the other, and vice versa. To the touch typist,
these deficiencies are maddening.

An "IBM PC compatible" may have a keyboard which does not
recognize every key combination a true IBM PC does,
e.g. shifted cursor keys. In addition, the "compatible"
vendors sometimes use proprietary keyboard interfaces,
preventing you from replacing the keyboard.

The 1981 PC had 360K floppy disks. In 1984, IBM introduced
the 1.2 megabyte floppy disk along with its AT model.
Although often used as backup storage, the high density
floppy is not often used for interchangeability. In 1986, IBM
introduced the 720K 3.5" microfloppy disk on its Convertible
laptop computer. It introduced the 1.44 megabyte double
density version with the PS/2 line. These disk drives can be
added to existing PCs.

Fixed, non-removable, hard disks for IBM compatibles are
available with storage capacities from 20 to over 600
megabytes. If a hard disk is added that is not compatible
with the existing disk controller, a new controller board
must be plugged in. However, one disk's internal standard
does not conflict with another, since all programs and data
must be copied onto it to begin with. Removable hard disks
that hold at least 20 megabytes are also available.

When a new peripheral device, such as a monitor or
scanner, is added to an IBM compatible, a corresponding, new
controller board must be plugged into an expansion slot (in
the bus) in order to electronically control its operation.
The PC and XT had eight-bit busses; the AT had a 16-bit bus.
16-bit boards will not fit into 8-bit slots, but 8-bit boards
will fit into 16-bit slots. Intel 80286 and Intel 80386
computers provide both 8-bit and 16-bit slots, while the 386s
also have proprietary 32-bit memory slots. The bus in
high-end models of the PS/2 line is called "Micro Channel".
EISA is a non-IBM rival to Micro Channel.

The original IBM PC came with BASIC in ROM. Later, Basic
and BasicA were distributed on floppy but ran and referenced
routines in ROM.

IBM PC

A PC made by IBM. In 1981, the first IBM PC was introduced with a colossal 16KB of RAM. However, the company was not that optimistic, projecting that 250,000 IBM PCs would sell in the first five years. In fact, three million were sold in that period, and the PC industry, first DOS and later Windows, would become the world's largest computer base.

Good Bye IBM PC In 2004, IBM exited the desktop and laptop arena when it sold its personal computer division to Lenovo, a major Chinese PC manufacturer. IBM retained its x86-based server market with its System x series until 2014, when Lenovo also acquired the line. See System x.

Names and Numbers IBM's first PCs had names such as PC, XT and AT, while its next-generation PS/2 line was given model numbers. For historical purposes, early IBM model designations are listed below. See PC, IBM-compatible PC, ThinkPad, IBM and Lenovo.

The Original IBM PC

This first model had two floppy disks and 16KB of RAM. Today, a smartphone has 150,000 times as much memory and more. (Image courtesy of IBM.)

The IBM PC Division's research and development of ThinkPad mobile computing technology takes place at the Yamato Laboratory in Kanagawa Prefecture, Japan and at development facilities in Research Triangle Park, North Carolina.

Prior to that, he held several senior executive positions including VP Business Operations for the IBM Personal Computer Group where he was responsible for all business strategy, development, and distribution operations/agreements, VP Development for IBM Personal Computer Group - where he was responsible for product line development including the IBM PC, AT, and PS-2 product groups.

During his tenure, he led the company's restructuring of its $7 billion PC business to form the IBM PC Company; he served on the IBM Corporate Executive Committee and Worldwide Management Council; and, he served on the board of IBM's integrated services and solutions company.

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